Bone fixation devices made of polymeric materials are today commonly used as pins, screws or pegs. One clinical problem encountered is that the pullout strength of these devices is quite low. To increase the holding strength, welding, e.g. by heat introduction of these polymeric implants is used. Depending on the anatomical shape or density of the bone, welding may not sufficiently increase the holding strength. Another clinical problem can arise due to thin or weak bone structures.